The invention relates to an electrical plug and socket assembly as defined in the preamble to claim 1. In this case, electrical plug and socket assembly particularly refers to an electrical line connection or an electrical device connection having a coupler connector and a portable socket-outlet.
A plug and socket device of this type, which is known, for example, from U.S. Pat. No. 5,637,010, serves the purpose of producing an electrical plug-in connection. To this end, a detachable electrical connection to a counter-contact part is produced by a plug contact part, for example in the form of a multi-pole coupler connector, that is connected to an electrical line. The counter-contact part, e.g., in the form of a portable socket-outlet, can also be connected to an electrical line, or directly to an electrical device.
To prevent contact between voltage-conducting parts, a plug and socket device of this type is frequently provided with a protective collar that projects beyond the voltage-conducting parts, and typically comprises an insulating material. The plug and socket device essentially includes an outside part, advantageously in the form of the plug part, and an inside part, which is received by the outside part and contains the counter-contacts of the plug and socket assembly in the form of sockets. The dimensions of the inside and outside parts are usually matched to one another such that the plug and socket assembly is held together by a non-positive lockup or a form-fit. To this end, the inside part that can be coupled to the outside part has a recess, into which a barb extends in the coupled state, the barb being held resiliently in a hole in the outside part, and secured against a radial deflection by its contact with a sleeve disposed to be axially displaced on the outside part.
In a plug and socket assembly known from U.S. Pat. No. 4,017,139, the axially-displaceable sleeve serves, on the one hand, to guard against an accidental loosening of the plug and socket assembly, and, on the other hand, to prevent an accidental coupling of the plug parts. From a resting or normal position, the sleeve can be displaced past this resting position, in and counter to the plug-in direction, up to a respective unlocking stop, so practically three stops are provided for the sleeve. This stipulates a complex, and therefore costly, locking mechanism, however.
It is therefore the object of the invention to disclose a locking mechanism for an electrical plug and socket assembly of the type mentioned at the outset, the mechanism being particularly reliable and having a comparatively simple design. The mechanism prevents an accidental separation of the two coupling parts, on the one hand, and permits a detachment of the plug and socket assembly that can be repeated as often as desired, on the other hand.
In accordance with the invention, this object is accomplished by the features of claim 1. Because the outside part has only two stops for the sleeve in the locked position and the unlocked position, the sleeve""s path of displacement on the shaft of the outside part is limited. In addition to the step on the shaft of the outside part, which forms the unlocked stop, at its end facing the insertion opening, the sleeve is provided with webs that are oriented inward and distributed over the inside circumference, and, in the locked position, rest against a retaining collar formed onto the outside part in the region of the insertion opening.
A plurality of resilient barbs, preferably two barbs located opposite one another, are preferably provided on the outside part of the plug and socket assembly, while the inside part has corresponding recesses for receiving the barbs. For the locking process, the barbs are blocked against a radial deflection by a sleeve that surrounds the outside part coaxially and is displaceable, being carried by the outside part. Unlocking is effected by the displacement of the sleeve counter to the plug-in or insertion direction. This releases the barbs, so they can move radially outward when the plug and socket assembly is decoupled.
A restoring spring is provided for maintaining the locking in the normal position, which is simply and advantageously achieved by the contact of the barbs with the inside wall of the sleeve. The spring is advantageously inserted into a closed, annular space between the outside part and the sleeve, which is advantageously limited by a web on the inside wall of the sleeve, and a step on the shaft of the outside part. To unlock the plug and socket assembly, the sleeve is displaced counter to the spring force, so the sleeve is always forced back into the normal, or locked, position.
The barb, or every barb, is advantageously formed from a cam and a resilient shaft (spring shaft) that are formed in one piece and disposed one behind the other in the axial direction, the shaft being molded in a hole in the outside part. The barb embodied in the manner of a cast-on spring tongue is thus self-resilient, and, in the normal position, is aligned with the wall that borders the insertion opening for the inside part. As an alternative, the barb can be deflected outward in the resting or normal position when the sleeve is retracted, and is thus prestressed when the barb is pressed in the direction of the interior chamber formed by the protective collar of the outside part when the sleeve is pushed forward, and the sleeve again fixes the barb against outward movement. This alternative simplifies the separation of the two plug connection or coupling parts.
The entrance inclination a of the barb can be less than the exit inclination. The entrance inclination should only deviate from a 0xc2x0 inclination by an amount that assures the joining of the inside and outside parts when the sleeve is in the unlocked position. The angle of inclination xcex1 is preferably between zero and 45 degrees.
Because the barb or locking hook has a two-legged spring shaft whose two spring legs, which support a cam or latch at the end, extend transversely to the radial direction of cam deflection, the locking mechanism operates in the manner of a directional locking mechanism. The spring legs lie in the plane of the hole in the outside part in which the barb is formed, the plane extending parallel to the insertion or joining direction. For guiding the cams or latches, the inside part has an inside contour that terminates in the recess. The inside contour tapers in the insertion direction toward the recess. This locking mechanism permits the outside part to be pushed onto the inside part without the sleeve being retracted into the unlocked position.
In contrast to a conventional snap connection of a directional locking mechanism described in terms of design and function in, for example, xe2x80x9cBauelemente der Feinmechanik [Precision Mechanics Components],xe2x80x9d O. Richter, R. v. Voss, F. Kozer, VEB Verlag Technik [Publisher] Berlin, 9th Edition (1964), pp. 283 et seq., the cams or barbs do not lie in the plane of the push guidance of the spring legs. lnstead, the cams are advantageously directed radially inward toward the receptacle chamb er for the inside part by 90xc2x0 from the plane of the push guidance, so the inside contour only forms one track guide with the cams. The spring legs themselves are not guided at the inside contour. For locking, the cams or latches therefore do not lock in cams or locking bars located next to the spring legs, but in the radially inward-oriented recess in the inside part. The locking mechanism thus permits the inside and outside parts to be coupled when the sleeve is in the locked position, which then reliably prevents a release of the plug and socket assembly. Furthermore, when the sleeve is retracted, the plug and socket assembly is unlocked in that the barbs can yield radially outward, thereby unlatching the cams, which are embodied as pull latches, from the counter-surface of the latching region.
The insertion end of the inside part supports a sealing ring for sealing the plug and socket assembly. To prevent the sealing ring from creating an obstruction when the two coupling parts are coupled, the inside part has at least two diameter steps, which decrease toward the insertion end; the step facing the insertion end is provided with a circumferential groove for receiving the sealing ring. The inside diameters of the outside part are adapated to these steps, assuring a reliable sealing effect after the plug and socket connection is produced.
The inside part has a plurality of axially-extending, throughgoing openings for receiving contact inserts, while throughgoing openings that are aligned with the axial openings are provided in the housing floor of the outside part in order to receive the counter-contact inserts. The outside part is advantageously embodied as a plug, while the inside part forms the socket. The reverse embodiment is also feasible, however. In this case, the jacket of the outside part, which limits the insertion opening, simultaneously forms the protective collar for preventing the plug contacts from bending due to external mechanical influences.
On the side of the jacket, the sleeve is provided with a circumferential recessed grip, which facilitates the manual displacement of the sleeve. To further facilitate the handling of the plug and socket assembly, a handle part is molded onto the end of the outside part located opposite the insertion opening, the part making a transition in one piece into a guide sleeve that is preferably bent at an oblique angle for receiving an electrical line.